Update: Calif.’s Rim Fire is Only 7% Contained

This Google map shows the proximity of the Rim Fire (shown in darker brown) to Yosemite National park.

Hundreds of firefighters were digging trenches, clearing brush and starting back blazes to keep a wildfire raging north of Yosemite National Park out of several mountain hamlets, The Associated Press reported.

Inaccessible terrain, strong winds and bone-dry conditions have hampered their efforts to contain the Rim Fire, which began Aug. 17 and has grown to become one of the biggest in California history.

Firefighters were hoping to advance on the flames Monday but strong winds were threatening push the blaze closer to Tuolumne City and nearby communities.

“This fire has continued to pose every challenge that there can be on a fire…,” said Daniel Berlant, a spokesman with the California Department of Forestry and Fire Protection. “It’s a very difficult firefight.”

The fire has consumed nearly 225 square miles of picturesque forests. Officials estimate containment at just 7%.

It continues burning in the remote wilderness area of Yosemite and is edging closer to the Hetch Hetchy Reservoir, the source of San Francisco’s famously pure drinking water, park spokesman Tom Medema said.

Despite ash falling like snowflakes on the reservoir and a thick haze of smoke limiting visibility to 100 feet, the quality of the water piped to the city 150 miles away is still good, say officials with the San Francisco Public Utilities Commission.

The city’s hydroelectric power generated by the system has been interrupted by the fire, forcing the utility to spend $600,000 buying power on the open market.

Park employees are continuing their efforts to protect two groves of giant sequoias that are unique to the region by cutting brush and setting sprinklers, Medema said.